Recently, the super-large diameter steel casing pile foundation of the Hongxingping Bridge in the Suichang PPP project in Zhejiang was successfully launched, marking the beginning of the construction of the underwater pile foundation. The maximum diameter of the variable-diameter pile used in the bridge is 3.9 meters, which is currently the largest pile foundation in the inner lake in China.A double-row parallel "traction + airbag" launching method was adopted in the steel casing pile, making it the first of its kind in China.

Due to traffic restrictions, the bridge steel casing pile foundation could not be transported to the construction site by ground transportation, and the large lifting equipment could not be used at the construction site, making it impossible to carry out on-site lifting and hoisting through shipping to install steel casing pile. In order to solve the problem, the project team found another way. They first transported steel plates with a total weight of more than 300 tons to the wharf in batches, processed them on the spot to make steel casings. In the second step, they independently developed a double-row parallel "traction + airbag" launching method, which was floated on the water to the pile position and then sunk as a whole. Through this transportation and installation method, the project team finally realized the successful launching of the steel casing pile foundation 20 days ahead of schedule.

The total length of the Hongxingping Bridge is about 34.4 kilometers, with about 4.5 kilometers of the connecting line. It adopts the standard construction of two-way two-lane secondary highway. Once completed, it will promote the economic development of the underdeveloped areas in western Suichang, and is of great significance to promoting the development of agricultural and tourism resources along the route.